After heating the breastmilk once not finished, can not be heated again to drink, easy to breed bacteria and change the effective nutrients. 1. Breastmilk is a very good bacterial petri dish, in the outside world is easy to breed a large number of bacteria, breastmilk in the 15 ~ 27 degrees Celsius room temperature for more than eight hours, the amount of disease-causing bacteria will increase significantly, and then heat can not completely remove the possible existence of disease-causing bacteria. It is not suitable for infants. 2. Repeated heating will also change the nutritional composition of breastmilk, heating for a long time, the surface of breastmilk will be a layer of milk skin, the bottom of the precipitation, resulting in the loss of important unsaturated fatty acids in breastmilk, repeated heating will also lead to protein deterioration. Breastmilk should be consumed by infants as early as possible, and should not be left for too long, so as not to jeopardize the health of infants.